PowerTrax No Slip

The lunch box type locker has always been considered too weak for the rear end:

re-install.

Dude, he's running 31's. 31's with an 8.25 are fine with a lunchbox, as your very own link admits.

Personally I think that the notion of lunch box lockers as too weak for the rear is a myth with newer more modern lunch box lockers anyhow. I don't know about the PowerTrax, but I have an Aussie Locker. The four solid pieces of steel that make up this locker are stronger than the four spider gears that they replaced. The cross-pin is a wear item but will have no more force on it than it had in its original configuration. I wouldn't want it in the back (I can very definitely feel it surging in the front when I plop the Jeep into 4x4 mode), but as long as you check the cross-pin with every differential fluid change and swap it out once you start seeing wear, you'll be fine. I suspect that the myth of the lunch box too weak for a rear end dates back to early Detroit Locker lunchboxes. For my Aussie Locker, it's clear that the axle shafts are going to break long before the locker itself does.

Take you movie camera with you: